Diversidade beta em comunidades de lagartos em duas ecorregiões distintas na Amazônia

Abstract

While it has been shown in recent years that the Amazon rainforest is not homogeneous, little is known about the effect of structural differences in the forest on species distributions. Loss still is known about the lizard species distribution patterns at mesoscales in the Amazon. Thus, this study aimed to evaluate the beta diversity in lizard communities, and their relationships with five environmental variables (altitude, slope, soil clay content, canopy openess and food availability). The study was carried out during the dry season, between September 2006 and March 2007, in two 25km2 areas in the northern Amazon, belonging to different ecorregions, which have large environmental heterogeneity, including areas of terrafirme forest, campina and campinarana. Three diurnal surveys were conducted in 59 plots of 250 meters long by visual encounter and searching the leaf litter. Lizard species composition, for abundance and presence/absence data, was represented by PCoA ordination axes, from Bray-Curtis and Sørensen association matrices, and inferential analyses were undertaken using MANCOVA and Multivariate Multiple Regression. The localities shared a large number of species, and the lizards communities did not show a clear pattern of species turnover, revealing low beta diversity associated to environmental heterogeneity. The major differences related to the species composition between the areas appear to be related to historical biogeographical relationships, and to the individual abundance to habitat heterogeneity. Only canopy openness and slope were associated with communities composition. It seems that, in the forest, the natural variation at scale of hectares is enough to maintain most species.